CN111894715B - Blockage detection method and system for SCR tail gas treatment system nozzle and vehicle - Google Patents

Blockage detection method and system for SCR tail gas treatment system nozzle and vehicle Download PDF

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CN111894715B
CN111894715B CN202010794224.XA CN202010794224A CN111894715B CN 111894715 B CN111894715 B CN 111894715B CN 202010794224 A CN202010794224 A CN 202010794224A CN 111894715 B CN111894715 B CN 111894715B
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nozzle
pressure
time period
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inlet pipe
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CN111894715A (en
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陈一平
何家明
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Shanghai Xingrong Automotive Technology Co ltd
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Shanghai Xingrong Automotive Technology Co ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/14—Arrangements for the supply of substances, e.g. conduits
    • F01N2610/1453—Sprayers or atomisers; Arrangement thereof in the exhaust apparatus
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

A blockage detection method for a nozzle of an SCR tail gas treatment system comprises the following steps: s101, detecting in the stage of reverse pumping and pressure discharging of the SCR tail gas treatment systemNozzle liquid inlet pipe in detection time period T1The pressure in the chamber, and calculating the time period T for the detection1Mean value of internal pressure
Figure DDA0002624918100000011
Wherein the detection time period T1In a time period T0Internal or with time period T0Same, the time period T0Time period t1 to t2 after nozzle opening; s102, passing the pressure average value
Figure DDA0002624918100000012
Judging the blockage condition of the nozzle: if it is
Figure DDA0002624918100000013
The nozzle is in a normal working state; if it is
Figure DDA0002624918100000014
The nozzle is in a slightly blocked state; if it is
Figure DDA0002624918100000015
The nozzle is in a severely clogged state. The invention can detect the nozzle blockage condition in real time in the reverse pumping stage, and can obtain more accurate and subdivided results compared with the existing two-state detection mode.

Description

Blockage detection method and system for SCR tail gas treatment system nozzle and vehicle
Technical Field
The invention belongs to the technical field of SCR tail gas treatment systems, and particularly relates to a blockage detection method and system for a nozzle of an SCR tail gas treatment system and a vehicle.
Background
With the continuous development and growth of automobile industry in China, the market share of commercial vehicles is also continuously promoted, and the demand and delivery of diesel engines serving as main power sources of the commercial vehicles are also increased year by year. The diesel engine has sufficient discharge capacity, excellent dynamic property and excellent fuel economy, and simultaneously has high pollution to the environment, so that the diesel engine becomes a problem to be solved urgently for vehicle emission control in China, China also starts to implement the national VI-stage emission standard of heavy diesel engines in the range of China from 7/1.2019, and manufacturers often adopt an SCR tail gas treatment system to reduce emission in order to achieve the purpose of reducing pollution in the working process of the diesel engine.
Selective Catalytic Reduction, SCR for short, is a technical principle of selectively reducing nitrogen oxides to nitrogen and water in an oxygen-rich environment by using a reducing agent under the action of a catalyst. The urea injection in SCR adopts a closed-loop injection strategy to realize the injection control of the engine in the steady-state and transient processes, and the urea injection quantity is adjusted and optimized through the operating parameters of the engine, such as the rotating speed, the fuel injection quantity, the exhaust flow, the exhaust temperature and the like.
When the SCR system works, the SCR system sequentially goes through three processes of pressure building, injection and back pumping. In the pressure building process, building pressure by a urea pump, and maintaining the urea pressure at about normal working pressure after the urea pressure is slowly increased; when the pressure of the system is built up, the system pressure is maintained at 0.5bar above and below the normal working pressure, when the system meets the injection condition, the engine control unit or the DCU sends out a urea nozzle opening instruction, when the engine finishes working, the key switch is powered off, the urea pump enters a reverse pumping stage, and in order to prevent the pipeline urea from being crystallized and blocked, the pump can suck residual urea in the pipeline and the nozzle back into the urea tank.
The nozzle of SCR system takes place to block up and can lead to the urea injection volume not enough, just also means that the oxidation-reduction reaction is incomplete in the tail gas treatment, and this one side can cause a large amount of pollutions to the environment, and on the other hand discharges that waste gas is not up to standard also can lead to the mistake of engine OBD system and restrict the maximum output torque of engine, and this not only can reduce the efficiency of vehicle operation, still can cause the influence to the security and the stability of driving, reduces driving efficiency, endangers driving safety. The existing SCR system can only carry out the binary detection of whether the nozzle is blocked.
Disclosure of Invention
In view of the above, the present invention provides a method and a system for detecting clogging of a nozzle of an SCR exhaust gas treatment system, and a vehicle.
In order to solve the technical problems, the invention adopts the following technical scheme:
a blockage detection method for a nozzle of an SCR tail gas treatment system comprises the following steps:
s101, in the stage of reverse pumping and pressure exhaust of the SCR tail gas treatment system, detecting a liquid inlet pipe of a nozzle in a detection time period T1The pressure in the chamber, and calculating the time period T for the detection1Mean value of internal pressure
Figure BDA0002624918080000021
Wherein the detection time period T1In a time period T0Internal or with time period T0Same, the time period T0Time period t1 to t2 after nozzle opening;
s102, passing the pressure average value
Figure BDA0002624918080000022
Judging the blockage condition of the nozzle:
if it is
Figure BDA0002624918080000023
The nozzle is in a normal working state;
if it is
Figure BDA0002624918080000024
The nozzle is in a slightly blocked state;
if it is
Figure BDA0002624918080000025
The nozzle is in a severely clogged state.
Wherein P1 is a preset first pressure threshold, and P2 is a preset second pressure threshold.
The t1 ═ 32 ± 2 seconds, the maximum value of t2 was 70 seconds, the P1 ═ 0.25bar, and the P2 ═ 0.45 bar.
The step S101 further includes: in the stage of the back pumping and discharging pressure of the SCR tail gas treatment system, the pressure of a liquid inlet pipe of the nozzle in a time period of 30 seconds to 40 seconds after the nozzle is opened is detected, and the average value of the pressure in the time period of 30 seconds to 40 seconds is calculated
Figure BDA0002624918080000026
This scheme still relates to a jam detecting system of SCR tail gas treatment system nozzle, including the storage module, the storage module includes many instructions loaded and executed by the treater:
s101, in the stage of reverse pumping and pressure exhaust of the SCR tail gas treatment system, detecting a liquid inlet pipe of a nozzle in a detection time period T1The pressure in the chamber, and calculating the time period T for the detection1Mean value of internal pressure
Figure BDA0002624918080000027
Wherein the detection time period T1In a time period T0Internal or with time period T0Same, the time period T0Time period t1 to t2 after nozzle opening;
s102, passing the pressure average value
Figure BDA0002624918080000031
Judging the blockage condition of the nozzle:
if it is
Figure BDA0002624918080000032
The nozzle is in a normal working state;
if it is
Figure BDA0002624918080000033
The nozzle is in a slightly blocked state;
if it is
Figure BDA0002624918080000034
The nozzle is in a severely clogged state.
Wherein P1 is a preset first pressure threshold, and P2 is a preset second pressure threshold.
The t1 ═ 32 ± 2 seconds, the maximum value of t2 was 70 seconds, the P1 ═ 0.25bar, and the P2 ═ 0.45 bar.
The step S101 further includes: in the stage of the back pumping and discharging pressure of the SCR tail gas treatment system, the pressure of a liquid inlet pipe of the nozzle in a time period of 30 seconds to 40 seconds after the nozzle is opened is detected, and the average value of the pressure in the time period of 30 seconds to 40 seconds is calculated
Figure BDA0002624918080000035
The present disclosure also relates to a vehicle having a blockage detection system for an SCR exhaust treatment system nozzle, the system comprising a memory module including a plurality of instructions loaded and executed by a processor:
s101, in the stage of reverse pumping and pressure exhaust of the SCR tail gas treatment system, detecting a liquid inlet pipe of a nozzle in a detection time period T1The pressure in the chamber, and calculating the time period T for the detection1Mean value of internal pressure
Figure BDA0002624918080000036
Wherein the detection time period T1In a time period T0Internal or with time period T0Same, the time period T0Time period t1 to t2 after nozzle opening;
s102, passing the pressure average value
Figure BDA0002624918080000037
Judging the blockage condition of the nozzle:
if it is
Figure BDA0002624918080000038
The nozzle is in a normal working state;
if it is
Figure BDA0002624918080000039
The nozzle is in a slightly blocked state;
if it is
Figure BDA00026249180800000310
The nozzle is in a severely clogged state.
Wherein P1 is a preset first pressure threshold, and P2 is a preset second pressure threshold.
The t1 ═ 32 ± 2 seconds, the maximum value of t2 was 70 seconds, the P1 ═ 0.25bar, and the P2 ═ 0.45 bar.
The step S101 further includes: in the stage of the back pumping and discharging pressure of the SCR tail gas treatment system, the pressure of a liquid inlet pipe of the nozzle in a time period of 30 seconds to 40 seconds after the nozzle is opened is detected, and the average value of the pressure in the time period of 30 seconds to 40 seconds is calculated
Figure BDA00026249180800000311
The invention can detect the nozzle blockage condition in real time in the reverse pumping stage, and can obtain more accurate and subdivided results compared with the existing two-state detection mode.
Drawings
The invention is described in detail below with reference to the following figures and detailed description:
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a schematic view of the internal structure of a urea pump;
FIG. 3 is a graph showing pressure changes in three sub-processes of the reverse pumping process of the nozzle inlet pipe when the nozzle is in a good condition;
FIG. 4 is a graph comparing pressure curves of the inlet pipe of the nozzle during the third sub-process of the reverse pumping process under the conditions of good condition and severe blockage of the nozzle;
FIG. 5 is a pressure average value of the present invention
Figure BDA0002624918080000041
A linear relationship with the degree of clogging.
Detailed Description
As shown in fig. 1, a method for detecting blockage of a nozzle of an SCR exhaust gas treatment system includes:
s101, in the stage of reverse pumping and pressure exhaust of the SCR tail gas treatment system, detecting a liquid inlet pipe of a nozzle in a detection time period T1The pressure in the chamber, and calculating the time period T for the detection1Mean value of internal pressure
Figure BDA0002624918080000042
Wherein the time period T is detected1In a time period T0Internal or with time period T0Same, time period T0The time period t1 to t2 after the nozzle is opened.
S102, passing pressure average value
Figure BDA0002624918080000043
Judging the blockage condition of the nozzle:
if it is
Figure BDA0002624918080000044
The nozzle is in a normal working state;
if it is
Figure BDA0002624918080000045
The nozzle is in a slightly blocked state;
if it is
Figure BDA0002624918080000046
The nozzle is in a severely clogged state.
Wherein P1 is a preset first pressure threshold, P2 is a preset second pressure threshold, and the two thresholds are detected for a time period T after the nozzles are opened by an SCR system which detects the completeness of the nozzles and an SCR system which detects the serious blockage of the nozzles in advance1The duty ratio of the internal reverse pump is obtained by respectively calculating the average value.
The invention utilizes the pressure change condition of the liquid inlet pipe of the nozzle to detect the blockage condition of the nozzle in the pressure discharge stage of the back-pumping process of the SCR tail gas treatment system.
Referring to fig. 2, at the beginning of the back-pumping process, the main pump M2 is always in the closed state, and the back-pumping pump M1 cooperates with the nozzle to back-pump and recycle the residual urea solution in the pipeline and the nozzle, and a total of three sub-processes are performed, as shown in table 1:
Figure BDA0002624918080000051
TABLE 1
The first process is as follows: natural pressure relief
The nozzle is closed, the reverse pumping pump M1 and the main pump M2 are both in a closed state, the urea solution naturally falls back to the urea box, and the pressure of the liquid inlet pipe of the nozzle naturally falls back.
And a second process: pump reverse pump
When the pressure of the nozzle liquid inlet pipe naturally falls back to a certain value, the back-suction pump M1 starts to work, the pressure of the nozzle liquid inlet pipe continuously drops, when the pressure drops to a certain limit value, the nozzle is opened, and then the process III is carried out.
The third process: inverted pumping injection pipe (inverted pumping pressure stage)
The reverse pump M1 continuously pumps the residual urea solution in the injection pipeline of the nozzle, and after the pressure of the liquid inlet pipe of the nozzle rises suddenly, different pressure change conditions exist according to different nozzle blockage states:
if the injector nozzle works normally and is not blocked, the pressure of the liquid inlet pipe of the nozzle is gradually increased to 0 (relative pressure) after the liquid inlet pipe of the nozzle is slightly raised.
If any one or more nozzles of the nozzle are blocked, the pressure of the liquid inlet pipe of the nozzle falls rapidly after a short rise and is kept low all the time and even continuously falls.
Taking a nozzle in a good state as an example, the pressure change trend of the liquid inlet pipe of the nozzle in the first, the second and the third processes of the back pumping process is shown in fig. 3, the x axis is time (second), the y axis is pressure (hectopa), and as the nozzle works well, when the nozzle is opened, the liquid inlet pipe of the nozzle is communicated with air, the relative pressure is close to 0, and the detection result of the pressure sensor is 0 (relative pressure).
As shown in fig. 4, it can be seen that the nozzle continues to work due to the back-suction pump under severe blockage, the pressure in the liquid inlet pipe of the nozzle will generate negative pressure due to suction force, and the nozzle which works well is connected with the external atmosphere, and the pressure after rising will be kept at about 0 (relative pressure).
Therefore, we can detect the time period T1Mean value of pressure in internal nozzle inlet pipe
Figure BDA0002624918080000061
Comparing with two threshold values obtained by experiment to judge the nozzleThe jam condition, see step S102.
The method can be used for detecting the nozzle blockage condition in real time in the reverse pumping stage, and compared with the existing two-state detection mode, the method can obtain more accurate and subdivided results so as to inform a driver of the results in time and upload the results to the cloud end for auxiliary analysis by the cloud end, thereby achieving quick response to the nozzle blockage fault.
It should be noted that, as can be seen from fig. 4, after the nozzle is opened, the pressure in the nozzle inlet pipe in the blocked state is lower than the pressure in the nozzle inlet pipe in the normal state throughout the entire period. The sequence of back pumping the injection tubes is as follows: when being full of liquid in the pipeline, firstly, the pure liquid of taking out, go to the mixture of taking out liquid and air again, extract the air at last, when taking out the pure liquid backward, whether the nozzle blocks up does not influence nozzle feed liquor intraductal pressure greatly, therefore the difference is not obvious, nozzle feed liquor intraductal pressure fluctuation may be unstable when taking out the liquid mixture backward, this also does not do benefit to the measurement, only when only taking out the air backward, under the certain circumstances of pump duty cycle that takes out backward, whether the nozzle blocks up influences the intraductal pressure of nozzle feed liquor huge, data of drawing this moment can make the difference show most, and the accuracy is improved.
By testing the nozzles with different degrees of blockage, urea solution in the nozzle liquid inlet pipe of the nozzle with different degrees of blockage can be completely pumped at t1 (32 +/-2 seconds) after the nozzle is opened in the stage of back pumping and discharging pressure, so that the pressure in the nozzle liquid inlet pipe only remains air pressure, and the accuracy of data extraction is high from the moment.
In this embodiment, the maximum value of t2 is 70 seconds, ensuring that the test is valid before the end of the back-pumping of the injection tube. The detection time period T can be set1Set to 20 seconds to 30 seconds, 20 seconds to 40 seconds, or 30 seconds to 70 seconds, and also set to 30 seconds to 50 seconds, or 35 seconds to 60 seconds, and of course, may be set to 50 seconds to 70 seconds.
In this example, P1 ═ 0.25bar and P2 ═ 0.45 bar.
The pressure of the liquid inlet pipe of the nozzle is collected by the pressure sensor and then curve simulation is carried out, and the curve simulation is carried out under the condition that the liquid inlet pipe is blocked to different degrees in the testPerforming fitting analysis and comparison on the obtained different pressure curves, performing linear correlation on the obtained residual error and the actual damage degree, and finally obtaining a conclusion: the average pressure of the nozzle liquid inlet pipe 30-40S after the pressure discharge stage is started (i.e. after the nozzle is opened) can be used as the most comprehensive performance index of the nozzle, and has typical difference and expression forms under different blockage conditions as parameters, and is the most suitable technical parameter for being used as a judgment standard, namely, the most suitable technical parameter is the best fit when the judgment is compared with the threshold value, so in the step S101, the pressure of the nozzle liquid inlet pipe in the time period of 30 seconds to 40 seconds after the nozzle is opened is preferably detected, and the average pressure value in the time period of 30 seconds to 40 seconds is calculated
Figure BDA0002624918080000071
See fig. 3 and 4.
When in use
Figure BDA0002624918080000072
The nozzle is in a normal operating condition.
If it is
Figure BDA0002624918080000073
The nozzle is in a slightly clogged state.
If it is
Figure BDA0002624918080000074
The nozzle is in a severely clogged state.
Preferably, as shown in FIG. 5, the present invention can pass the pressure average value
Figure BDA0002624918080000075
And the linear relation with the blockage degree, and scoring (such as percentile system, 60-point passing or ABC rating) for more concrete and visual blockage conditions.
This scheme still relates to a jam detecting system of SCR tail gas treatment system nozzle, including the storage module, the storage module includes many instructions of being loaded and carrying out by the treater, refer to fig. 1:
s101, in the stage of reverse pumping and pressure exhausting of the SCR tail gas treatment system,detecting nozzle liquid inlet pipe in detecting time period T1The pressure in the chamber, and calculating the time period T for the detection1Mean value of internal pressure
Figure BDA0002624918080000076
Wherein the time period T is detected1In a time period T0Internal or with time period T0Same, time period T0The time period t1 to t2 after the nozzle is opened.
S102, passing pressure average value
Figure BDA0002624918080000077
Judging the blockage condition of the nozzle:
if it is
Figure BDA0002624918080000078
The nozzle is in a normal working state;
if it is
Figure BDA0002624918080000079
The nozzle is in a slightly blocked state;
if it is
Figure BDA00026249180800000710
The nozzle is in a severely clogged state.
Wherein P1 is a preset first pressure threshold, P2 is a preset second pressure threshold, and the two thresholds are detected for a time period T after the nozzles are opened by an SCR system which detects the completeness of the nozzles and an SCR system which detects the serious blockage of the nozzles in advance1The duty ratio of the internal reverse pump is obtained by respectively calculating the average value.
The invention utilizes the pressure change condition of the liquid inlet pipe of the nozzle to detect the blockage condition of the nozzle in the pressure discharge stage of the back-pumping process of the SCR tail gas treatment system.
Referring to fig. 2, at the beginning of the back-pumping process, the main pump M2 is always in the closed state, and the back-pumping pump M1 cooperates with the nozzle to back-pump and recycle the residual urea solution in the pipeline and the nozzle, and a total of three sub-processes are performed, as shown in table 1:
Figure BDA0002624918080000081
TABLE 1
The first process is as follows: natural pressure relief
The nozzle is closed, the reverse pumping pump M1 and the main pump M2 are both in a closed state, the urea solution naturally falls back to the urea box, and the pressure of the liquid inlet pipe of the nozzle naturally falls back.
And a second process: pump reverse pump
When the pressure of the nozzle liquid inlet pipe naturally falls back to a certain value, the back-suction pump M1 starts to work, the pressure of the nozzle liquid inlet pipe continuously drops, when the pressure drops to a certain limit value, the nozzle is opened, and then the process III is carried out.
The third process: inverted pumping injection pipe (inverted pumping pressure stage)
The reverse pump M1 continuously pumps the residual urea solution in the injection pipeline of the nozzle, and after the pressure of the liquid inlet pipe of the nozzle rises suddenly, different pressure change conditions exist according to different nozzle blockage states:
if the injector nozzle works normally and is not blocked, the pressure of the liquid inlet pipe of the nozzle is gradually increased to 0 (relative pressure) after the liquid inlet pipe of the nozzle is slightly raised.
If any one or more nozzles of the nozzle are blocked, the pressure of the liquid inlet pipe of the nozzle falls rapidly after a short rise and is kept low all the time and even continuously falls.
Taking a nozzle in a good state as an example, the pressure change trend of the liquid inlet pipe of the nozzle in the first, the second and the third processes of the back pumping process is shown in fig. 3, the x axis is time (second), the y axis is pressure (hectopa), and as the nozzle works well, when the nozzle is opened, the liquid inlet pipe of the nozzle is communicated with air, the relative pressure is close to 0, and the detection result of the pressure sensor is 0 (relative pressure).
As shown in fig. 4, it can be seen that the nozzle continues to work due to the back-suction pump under severe blockage, the pressure in the liquid inlet pipe of the nozzle will generate negative pressure due to suction force, and the nozzle which works well is connected with the external atmosphere, and the pressure after rising will be kept at about 0 (relative pressure).
Therefore, we can detect the time period T1Mean value of pressure in internal nozzle inlet pipe
Figure BDA0002624918080000082
Comparing with two threshold values obtained by experiment, judging the blocking state of the nozzle, see step S102.
The method can be used for detecting the nozzle blockage condition in real time in the reverse pumping stage, and compared with the existing two-state detection mode, the method can obtain more accurate and subdivided results so as to inform a driver of the results in time and upload the results to the cloud end for auxiliary analysis by the cloud end, thereby achieving quick response to the nozzle blockage fault.
It should be noted that, as can be seen from fig. 4, after the nozzle is opened, the pressure in the nozzle inlet pipe in the blocked state is lower than the pressure in the nozzle inlet pipe in the normal state throughout the entire period. The sequence of back pumping the injection tubes is as follows: when being full of liquid in the pipeline, firstly, the pure liquid of taking out, go to the mixture of taking out liquid and air again, extract the air at last, when taking out the pure liquid backward, whether the nozzle blocks up does not influence nozzle feed liquor intraductal pressure greatly, therefore the difference is not obvious, nozzle feed liquor intraductal pressure fluctuation may be unstable when taking out the liquid mixture backward, this also does not do benefit to the measurement, only when only taking out the air backward, under the certain circumstances of pump duty cycle that takes out backward, whether the nozzle blocks up influences the intraductal pressure of nozzle feed liquor huge, data of drawing this moment can make the difference show most, and the accuracy is improved.
By testing the nozzles with different degrees of blockage, urea solution in the nozzle liquid inlet pipe of the nozzle with different degrees of blockage can be completely pumped at t1 (32 +/-2 seconds) after the nozzle is opened in the stage of back pumping and discharging pressure, so that the pressure in the nozzle liquid inlet pipe only remains air pressure, and the accuracy of data extraction is high from the moment.
In this embodiment, the maximum value of t2 is 70 seconds, ensuring that the test is valid before the end of the back-pumping of the injection tube. The detection time period T can be set1Set to 20 seconds to 30 seconds, 20 seconds to 40 seconds, or 30 seconds to 70 seconds, and also set to 30 seconds to 50 seconds, or 35 seconds to 60 seconds, and of course, may be set to 50 seconds to 70 seconds.
In this example, P1 ═ 0.25bar and P2 ═ 0.45 bar.
The pressure of the nozzle liquid inlet pipe is collected through the pressure sensor and then curve simulation is carried out, fitting analysis and comparison are carried out on different pressure curves obtained under different degrees of blockage conditions in the test, linear correlation is carried out on the obtained residual error and the actual damage degree, and finally the conclusion is obtained: the average pressure of the nozzle liquid inlet pipe 30-40S after the pressure discharge stage is started (i.e. after the nozzle is opened) can be used as the most comprehensive performance index of the nozzle, and has typical difference and expression forms under different blockage conditions as parameters, and is the most suitable technical parameter for being used as a judgment standard, namely, the most suitable technical parameter is the best fit when the judgment is compared with the threshold value, so in the step S101, the pressure of the nozzle liquid inlet pipe in the time period of 30 seconds to 40 seconds after the nozzle is opened is preferably detected, and the average pressure value in the time period of 30 seconds to 40 seconds is calculated
Figure BDA0002624918080000101
See fig. 3 and 4.
When in use
Figure BDA0002624918080000102
The nozzle is in a normal operating condition.
If it is
Figure BDA0002624918080000103
The nozzle is in a slightly clogged state.
If it is
Figure BDA0002624918080000104
The nozzle is in a severely clogged state.
Preferably, as shown in FIG. 5, the present invention can pass the pressure average value
Figure BDA0002624918080000105
Linear relationship with degree of clogging, versus cloggingThe condition is scored more specifically and visually (e.g., percentile, 60-point pass or ABC rating).
The invention also relates to a vehicle having a blockage detection system for a nozzle of an SCR exhaust gas treatment system, the system comprising a memory module comprising a plurality of instructions loaded and executed by a processor, see fig. 1:
s101, in the stage of reverse pumping and pressure exhaust of the SCR tail gas treatment system, detecting a liquid inlet pipe of a nozzle in a detection time period T1The pressure in the chamber, and calculating the time period T for the detection1Mean value of internal pressure
Figure BDA0002624918080000106
Wherein the time period T is detected1In a time period T0Internal or with time period T0Same, time period T0The time period t1 to t2 after the nozzle is opened.
S102, passing pressure average value
Figure BDA0002624918080000107
Judging the blockage condition of the nozzle:
if it is
Figure BDA0002624918080000108
The nozzle is in a normal working state;
if it is
Figure BDA0002624918080000109
The nozzle is in a slightly blocked state;
if it is
Figure BDA00026249180800001010
The nozzle is in a severely clogged state.
Wherein P1 is a preset first pressure threshold, P2 is a preset second pressure threshold, and the two thresholds are detected for a time period T after the nozzles are opened by an SCR system which detects the completeness of the nozzles and an SCR system which detects the serious blockage of the nozzles in advance1The duty ratio of the internal reverse pump is obtained by respectively calculating the average value.
The invention utilizes the pressure change condition of the liquid inlet pipe of the nozzle to detect the blockage condition of the nozzle in the pressure discharge stage of the back-pumping process of the SCR tail gas treatment system.
Referring to fig. 2, at the beginning of the back-pumping process, the main pump M2 is always in the closed state, and the back-pumping pump M1 cooperates with the nozzle to back-pump and recycle the residual urea solution in the pipeline and the nozzle, and a total of three sub-processes are performed, as shown in table 1:
Figure BDA0002624918080000111
TABLE 1
The first process is as follows: natural pressure relief
The nozzle is closed, the reverse pumping pump M1 and the main pump M2 are both in a closed state, the urea solution naturally falls back to the urea box, and the pressure of the liquid inlet pipe of the nozzle naturally falls back.
And a second process: pump reverse pump
When the pressure of the nozzle liquid inlet pipe naturally falls back to a certain value, the back-suction pump M1 starts to work, the pressure of the nozzle liquid inlet pipe continuously drops, when the pressure drops to a certain limit value, the nozzle is opened, and then the process III is carried out.
The third process: inverted pumping injection pipe (inverted pumping pressure stage)
The reverse pump M1 continuously pumps the residual urea solution in the injection pipeline of the nozzle, and after the pressure of the liquid inlet pipe of the nozzle rises suddenly, different pressure change conditions exist according to different nozzle blockage states:
if the injector nozzle works normally and is not blocked, the pressure of the liquid inlet pipe of the nozzle is gradually increased to 0 (relative pressure) after the liquid inlet pipe of the nozzle is slightly raised.
If any one or more nozzles of the nozzle are blocked, the pressure of the liquid inlet pipe of the nozzle falls rapidly after a short rise and is kept low all the time and even continuously falls.
Taking a nozzle in a good state as an example, the pressure change trend of the liquid inlet pipe of the nozzle in the first, the second and the third processes of the back pumping process is shown in fig. 3, the x axis is time (second), the y axis is pressure (hectopa), and as the nozzle works well, when the nozzle is opened, the liquid inlet pipe of the nozzle is communicated with air, the relative pressure is close to 0, and the detection result of the pressure sensor is 0 (relative pressure).
As shown in fig. 4, it can be seen that the nozzle continues to work due to the back-suction pump under severe blockage, the pressure in the liquid inlet pipe of the nozzle will generate negative pressure due to suction force, and the nozzle which works well is connected with the external atmosphere, and the pressure after rising will be kept at about 0 (relative pressure).
Therefore, we can detect the time period T1Mean value of pressure in internal nozzle inlet pipe
Figure BDA0002624918080000112
Comparing with two threshold values obtained by experiment, judging the blocking state of the nozzle, see step S102.
The method can be used for detecting the nozzle blockage condition in real time in the reverse pumping stage, and compared with the existing two-state detection mode, the method can obtain more accurate and subdivided results so as to inform a driver of the results in time and upload the results to the cloud end for auxiliary analysis by the cloud end, thereby achieving quick response to the nozzle blockage fault.
It should be noted that, as can be seen from fig. 4, after the nozzle is opened, the pressure in the nozzle inlet pipe in the blocked state is lower than the pressure in the nozzle inlet pipe in the normal state throughout the entire period. The sequence of back pumping the injection tubes is as follows: when being full of liquid in the pipeline, firstly, the pure liquid of taking out, go to the mixture of taking out liquid and air again, extract the air at last, when taking out the pure liquid backward, whether the nozzle blocks up does not influence nozzle feed liquor intraductal pressure greatly, therefore the difference is not obvious, nozzle feed liquor intraductal pressure fluctuation may be unstable when taking out the liquid mixture backward, this also does not do benefit to the measurement, only when only taking out the air backward, under the certain circumstances of pump duty cycle that takes out backward, whether the nozzle blocks up influences the intraductal pressure of nozzle feed liquor huge, data of drawing this moment can make the difference show most, and the accuracy is improved.
By testing the nozzles with different degrees of blockage, urea solution in the nozzle liquid inlet pipe of the nozzle with different degrees of blockage can be completely pumped at t1 (32 +/-2 seconds) after the nozzle is opened in the stage of back pumping and discharging pressure, so that the pressure in the nozzle liquid inlet pipe only remains air pressure, and the accuracy of data extraction is high from the moment.
In this embodiment, the maximum value of t2 is 70 seconds, ensuring that the test is valid before the end of the back-pumping of the injection tube. The detection time period T can be set1Set to 20 seconds to 30 seconds, 20 seconds to 40 seconds, or 30 seconds to 70 seconds, and also set to 30 seconds to 50 seconds, or 35 seconds to 60 seconds, and of course, may be set to 50 seconds to 70 seconds.
In this example, P1 ═ 0.25bar and P2 ═ 0.45 bar.
The pressure of the nozzle liquid inlet pipe is collected through the pressure sensor and then curve simulation is carried out, fitting analysis and comparison are carried out on different pressure curves obtained under different degrees of blockage conditions in the test, linear correlation is carried out on the obtained residual error and the actual damage degree, and finally the conclusion is obtained: the average pressure of the nozzle liquid inlet pipe 30-40S after the pressure discharge stage is started (i.e. after the nozzle is opened) can be used as the most comprehensive performance index of the nozzle, and has typical difference and expression forms under different blockage conditions as parameters, and is the most suitable technical parameter for being used as a judgment standard, namely, the most suitable technical parameter is the best fit when the judgment is compared with the threshold value, so in the step S101, the pressure of the nozzle liquid inlet pipe in the time period of 30 seconds to 40 seconds after the nozzle is opened is preferably detected, and the average pressure value in the time period of 30 seconds to 40 seconds is calculated
Figure BDA0002624918080000131
See fig. 3 and 4.
When in use
Figure BDA0002624918080000132
The nozzle is in a normal operating condition.
If it is
Figure BDA0002624918080000133
The nozzle is in a slightly clogged state.
If it is
Figure BDA0002624918080000134
The nozzle is in a severely clogged state.
Preferably, as shown in FIG. 5, the present invention can pass the pressure average value
Figure BDA0002624918080000135
And the linear relation with the blockage degree, and scoring (such as percentile system, 60-point passing or ABC rating) for more concrete and visual blockage conditions.
However, those skilled in the art should realize that the above embodiments are illustrative only and not limiting to the present invention, and that changes and modifications to the above described embodiments are intended to fall within the scope of the appended claims, provided they fall within the true spirit of the present invention.

Claims (6)

1. A blockage detection method for a nozzle of an SCR tail gas treatment system is characterized by comprising the following steps:
s101, in the stage of reverse pumping and pressure exhaust of the SCR tail gas treatment system, detecting a liquid inlet pipe of a nozzle in a detection time period T1The pressure in the chamber, and calculating the time period T for the detection1Mean value of internal pressure
Figure FDA0003199512530000011
Wherein the detection time period T1In a time period T0Internal or with time period T0Same, the time period T0Time period t1 to t2 after nozzle opening;
s102, passing the pressure average value
Figure FDA0003199512530000012
Judging the blockage condition of the nozzle:
if it is
Figure FDA0003199512530000013
The nozzle is in a normal working state;
if it is
Figure FDA0003199512530000014
The nozzle is in a slightly blocked state;
if it is
Figure FDA0003199512530000015
The nozzle is in a severely clogged state;
wherein P1 is a preset first pressure threshold, and P2 is a preset second pressure threshold;
the t1 ═ 32 ± 2 seconds, the maximum value of t2 was 70 seconds, the P1 ═ 0.25bar, and the P2 ═ 0.45 bar.
2. The method of claim 1, wherein step S101 further comprises: in the stage of the back pumping and discharging pressure of the SCR tail gas treatment system, the pressure of a liquid inlet pipe of the nozzle in a time period of 30 seconds to 40 seconds after the nozzle is opened is detected, and the average value of the pressure in the time period of 30 seconds to 40 seconds is calculated
Figure FDA0003199512530000016
3. A blockage detection system for an SCR exhaust treatment system nozzle, comprising a memory module including a plurality of instructions loaded and executed by a processor:
s101, in the stage of reverse pumping and pressure exhaust of the SCR tail gas treatment system, detecting a liquid inlet pipe of a nozzle in a detection time period T1The pressure in the chamber, and calculating the time period T for the detection1Mean value of internal pressure
Figure FDA0003199512530000017
Wherein the detection time period T1In a time period T0Internal or with time period T0Same, the time period T0Time period t1 to t2 after nozzle opening;
S102、by said pressure mean value
Figure FDA0003199512530000018
Judging the blockage condition of the nozzle:
if it is
Figure FDA0003199512530000019
The nozzle is in a normal working state;
if it is
Figure FDA00031995125300000110
The nozzle is in a slightly blocked state;
if it is
Figure FDA0003199512530000021
The nozzle is in a severely clogged state;
wherein P1 is a preset first pressure threshold, and P2 is a preset second pressure threshold;
the t1 ═ 32 ± 2 seconds, the maximum value of t2 was 70 seconds, the P1 ═ 0.25bar, and the P2 ═ 0.45 bar.
4. The system of claim 3, wherein step S101 further comprises: in the stage of the back pumping and discharging pressure of the SCR tail gas treatment system, the pressure of a liquid inlet pipe of the nozzle in a time period of 30 seconds to 40 seconds after the nozzle is opened is detected, and the average value of the pressure in the time period of 30 seconds to 40 seconds is calculated
Figure FDA0003199512530000022
5. A vehicle characterized by a blockage detection system having an SCR exhaust treatment system nozzle, the system comprising a memory module including a plurality of instructions loaded and executed by a processor:
s101, detecting that a liquid inlet pipe of a nozzle is detected in a reverse pumping and pressure-discharging stage of an SCR tail gas treatment systemTime interval T1The pressure in the chamber, and calculating the time period T for the detection1Mean value of internal pressure
Figure FDA0003199512530000023
Wherein the detection time period T1In a time period T0Internal or with time period T0Same, the time period T0Time period t1 to t2 after nozzle opening;
s102, passing the pressure average value
Figure FDA0003199512530000024
Judging the blockage condition of the nozzle:
if it is
Figure FDA0003199512530000025
The nozzle is in a normal working state;
if it is
Figure FDA0003199512530000026
The nozzle is in a slightly blocked state;
if it is
Figure FDA0003199512530000027
The nozzle is in a severely clogged state;
wherein P1 is a preset first pressure threshold, and P2 is a preset second pressure threshold;
the t1 ═ 32 ± 2 seconds, the maximum value of t2 was 70 seconds, the P1 ═ 0.25bar, and the P2 ═ 0.45 bar.
6. The vehicle of claim 5, wherein step S101 further comprises: in the stage of the back pumping and discharging pressure of the SCR tail gas treatment system, the pressure of a liquid inlet pipe of the nozzle in a time period of 30 seconds to 40 seconds after the nozzle is opened is detected, and the average value of the pressure in the time period of 30 seconds to 40 seconds is calculated
Figure FDA0003199512530000028
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